1. Field of the Invention
The present invention generally relates to an oil activated fuel injector and, more particularly, to an oil activated electronically or mechanically controlled fuel injector control with a delay plunger.
2. Background Description
There are many types of fuel injectors designed to inject fuel into a combustion chamber of an engine. For example, fuel injectors may be mechanically, electrically or hydraulically controlled in order to inject fuel into the combustion chamber of the engine. In the hydraulically actuated systems, a control valve body may be provided with two, three or four way valve systems, each having grooves or orifices which allow fluid communication between working ports, high pressure ports and venting ports of the control valve body of the fuel injector and the inlet area. The working fluid is typically engine oil or other types of suitable hydraulic fluid which is capable of providing a pressure within the fuel injector in order to begin the process of injecting fuel into the combustion chamber.
In current designs, a driver will deliver a current or voltage to an open side of an open coil solenoid. The magnetic force generated in the open coil solenoid will shift a spool into the open position so as to align grooves or orifices (hereinafter referred to as “grooves”) of the control valve body and the spool. The alignment of the grooves permits the working fluid to flow into an intensifier chamber from an inlet portion of the control valve body (via working ports). The high pressure working fluid then acts on an intensifier piston to compress an intensifier spring and hence compress fuel located within a high pressure plunger chamber. As the pressure in the high pressure plunger chamber increases, the fuel pressure will begin to rise above a needle check valve opening pressure. At the prescribed fuel pressure level, the needle check valve will shift against the needle spring and open the injection holes in a nozzle tip. The fuel will then be injected into the combustion chamber of the engine.
However, in such a conventional system, a small quantity (pilot injection) of fuel cannot be efficiently injected into the engine during a pre-stroke phase of the plunger. This leads to higher emissions and engine noise. The smaller quantities of fuel cannot be efficiently injected into the engine because once the solenoid valve of the injector is opened a larger quantity of fuel is injected into the engine. To provide a smaller quantity of fuel, a delay of the pre-stroke of the plunger must be provided. But, this can only be provided in the conventional system by adding more working fluid, under high pressure, into the injector. The additional pressurized working fluid may cause a delay; however, additional energy from the high pressure oil pump must be expanded in order to provide this additional working fluid. This leads to an inefficiency in the operations of the fuel injector, itself, and also does not provide a consistent supply of fuel into the engine.
The present invention is directed to overcoming one or more of the problems as set forth above.